The present invention relates to a method and apparatus for controlling a vehicle actuatable occupant restraining device.
Air bag restraining systems in vehicles for vehicle occupants are known in the art. An air bag restraining device may include a multistage inflator where the stages are actuated at different times in response to vehicle crash conditions.
U.S. Pat. No. 5,935,182 to Foo et al., assigned to TRW Inc., discloses a method and apparatus for discriminating a vehicle crash condition using virtual sensing. U.S. Pat. No. 6,036,225 to Foo et al., assigned to TRW Inc., discloses a method and apparatus for controlling a multistage actuatable restraining system in a vehicle using crash severity index values. U.S. Pat. No. 6,186,539 to Foo et al., also assigned to TRW Inc., discloses a method and apparatus for controlling a multistage actuatable restraining device using crash severity indexing and crush zone sensors.
The present invention is directed to a method and apparatus for controlling a vehicle multistage actuatable occupant restraining system. A crash sensor senses crash acceleration and provides a crash acceleration signal indicative thereof. Crash velocity and crash displacement are determined in response to the crash acceleration signal. A first stage of the multistage actuatable occupant restraining system is actuated in response to the determined crash velocity as a function of crash displacement exceeding a low threshold. A crush zone accelerometer senses crash acceleration at a crush zone location. The crush zone acceleration as a function of the crash displacement is compared against a crush zone threshold. The value of the low threshold is switched to a different value when the crush zone acceleration exceeds the crush zone threshold.